Spirit level



June 1, 1954 s. T. ROBERTS SPIRIT LEVEL Filed April 23, 1952 Patented June l, 1954 UNITED STATES PATENT OFFICE Claims. 1

This invention relates to spirit levels, and it relates more particularly to the construction and arrangement of the stocks of spirit levels, and to the mounting of the bubble cells therein.

Heretofore it has been customary to make the stocks of spirit levels of wood, which wood should be straight grained, free from knots, and well seasoned. It is becoming increasingly diiicult to obtain wood of the proper quality and condition, and in most instances the manufacturers of spirit levels have to resort to the use of opaque enamels and other finishes to cover the more or less imperfect wood which must now be used if the level stocks are to be made of wood.

Stocks made of metal such, for example, as aluminum or the like, require expensive machine operations, involve difficulties of mounting the bubble cells, and many times the desired metal is not available.

The principal object of the present invention is to provide a spirit level of a novel construction, the stock of which may be made of extruded plastic or other suitably shaped pieces of ma# terial.

A further object of the invention is to provide a spirit level the parts of which may be inexpensively assembled, and which when so assembled, will be reasonably accurate.

A further object of the invention is to provide a spirit level having the bubble cells mounted therein in a novel manner which will obviate the necessity of adjusting the cells in the stock.

A further object of the invention is to provide a spirit level having bubble cells of a novel form which may be inexpensively made.

The nature and characteristic features of the present invention will be more readily understood from the following description, taken in connection with the accompanying drawing forming part hereof, in which:

Figure l is a side elevation of a spirit level embodying the main features of the present invention.

Fig. 2 is a horizontal section thereof, enlarged, taken on the line 2-2 of Fig. l;

Fig. 3 is a transverse section, also enlarged, taken on the line 3 3 of Fig. 1;

Fig. 4 is a similar view, the section being taken on the line li-4 of Fig. 1;

Fig. 5 is a similar view, the section being taken on the line 5-5 of Fig. 1; and

Fig. 6 is a view of the several parts of a preferred form of bubble cell, the parts being shown in separated relationship before they are united to each other.

It should, of course, be understood that the description and drawing herein are illustrative merely, and that various modifications and changes may be made in the structure disclosed without departing from the spirit of the inven tion.

The stock of the spirit level of the present invention comprises edgemembers I, each having an outer working face II. The s ide faces I2 of each member Il] are preferably beveled as in-y dicated in Figs. 3, l and 5 of the drawing. Each of the edge members has an internal dovetail groove I3, and also a larger groove I4 to provide shoulders I5 along its inner face.

The central or web structure is preferably made of a plurality of pieces which, in each instance, would be one or more than the number of bubble cells mounted in the stock.

The pieces I 6 of the web structure, at each end of the stock, each have one end squared as at Il to provide the outer ends of the web portion of the stock, and the other or inner end I I3v of eachpiece I6 of the web structure is shaped complemental to the particular shape of the cell member employed, which will-be hereinafter more fully described.

Likewise, each of the intermediate pieces I9 of the web structure is shaped at its respective ends as at 20 complemental to the shape of the bubble cells at the respective ends thereof.

Each of the pieces I6 and I9 of the web structure is preferably at as at 2I and with its edge portions 22 shaped complemental to the inner grooves I3 and I4 in the edge members I0.

The bubble cells are preferably made of two similar parts 30 molded of transparent plastic of the acrylic resin type, and each of said bubble cells has its perimeter 3| of non-circular shape when assembled.

Each bubble cell 30 may be of any non-circular shape, but preferably has an elliptical perimeter, as shown in the drawing, although any other non-circular form may be used which will be non-rotative in the stock when the level is completely assembled.

The preferred type of bubble cell is shown with the parts in separated relationship in Fig. 6 of the drawing and, as there shown, each part comprises side walls 32, each semi-elliptical in outline, and each part is shaped at its abutting portion to provide an internal barrel shaped cavity 33 adapted to contain the liquid to provide the bubble.

Each part of the bubble cell is provided at one end with a semi-circular groove 34 extending from the internal cavity 33- to the exterior, thereby to provide a passageway through which the bubble liquid may be introduced after the two parts are cemented to each other, and which may then be sealed by means of a suitable plug 35 cemented in the passageway provided by the grooves 34.

On each side of each of the bubble cells there is preferably mounted aglass cover ,plate 36 which serves to `preventzthe relatively soit acrylic resin, of which the 'bubble cell is made, 'from being scratched in use.

The respective ends of the several pieces I5 and I9 of the web structure are shaped complemental to the bubble cell which is confined between said ends at desired locations.

In the manufacture of the levelsiof Athe present I invention the bubble cells are iirst separately molded and assembled. The edge members of the stock are cut to the desired lengths, and the web pieces are cut :to their required lengths :and shaped at the ends thereof as hereinbefore :set forth.

The Yweb pieces of the stock are then `brought together ;by.sliding the same in the grooves-of the edge members coniining a bubble cell adjacent the ends-of each 4pair of `recesoi ithe 'web ystructure. The partsarecemented to each-other.

Howeventhe web portion of lthe stockmay be made of-asinglepiece of material, and the openingsfor the bubble cells -may be cut'therein, in whichcaseit will of coursebe necessary that said openings for the bubblecells -be shaped the Ysame as the perimeters ,of the bubble cells .which are to be placed therein.

It Iwill be seen that, by :the ,present invention, there is cprovided a simple, durable and eiiicient form of spirit level `which .may vbe inexpensively made, whichwhen assembled will beof a permanent and lasting nharacter, -and which Vwill not only .be initially accurate, but will also maintain its accuracy throughout .its nsefullife.

I claim:

1. A*Aspirit.leVeleomprsing separate edgemem- ,bers each provided with an` outer working surface, and an inner web structure in dovetail fengage ment with vtheedge .membersthefinner web structure Abeing ,provided vwith :non-circular openings, and .bubblecells positioned ,in said openings, ,each of said bubble cells being iixedlyfpositioned-in its opening .by having its 4perimeter .complemental to ,and fitting lsaid opening.

.2. A spirit levelcomprisingseparate edgemem.- bers each providedwithanouter working surface, ,and an inner web structurecomprisinga `plurality .of pieces .in dovetail engagement with .theedge members, `the abutting .ends Yof each `adjacent ,pair of web pieces being shaped .to provide nonfmembers,therabuttingtends'of :eachadjacent pair of web pieces being shaped to provide non-circular npenings, and bubble cells positioned in said openings, each of said bubble cells being xedly posiitioned in its opening by having its perimeter complemental to and tting said opening.

4. A'spiritlevel comprising separate edge memherseach provided with an outer working surface, and an inner web structure comprising a plurality :of pieces in dovetail engagement with the edge members, the abutting ends of each adjacent pair=of webpieces being shapedto provide non-circular openings, and bubble cells positioned in said cpeningsfeach of said bubble cells being lxedly positioned inits opening byhaving its perimeter ccmplemental to ,and fitting "said opening,andeach offsaid bubble 'cells comprising molded `transparent :members Vsecured to -each other in 1a transverse :plane and formed to Ipro- ,videan'internal cavityto receive the-bubble fluid.

r5. A Vspirit level Acomprising separate'edge members each provided with. an cuter working surface, and an inner web-structure comprising a plurality 'offpiecesinidovetail .engagement with vthe edge members, the abuttingends of eachiadjacent` pair of Web 'pieces `being shaped @to provide non-circularcpenings, and bubble -cells positioned Ain said openings, feach of -said -bubble .cells being iixedly positioned in its opening by having its `perimeter complemental to and fitting said opening, and eaclr of said-bubble cells comprising 'a Vpair of molded transparent members secured `to each other -in a transverse plane and formed to proyide an :internal elongated :barrel shaped .cavity to receive the bubble uid, said cavity having its .longitudinal axis A4.disposed -in said plane.

.References Cited .in the le .of .this patent UNITED STATES PATENTS Number Name Date 651,142 Keuifel June"5 1900 1,690,053 Charlton Oct. 30, 1920 2,305,678 Cravaritis Dec. '22, 1942 '2,487,245 Hubbard Nov. 8, 1949 FOREIGN PATENTS Number Country Date .258;624 Switzerland May 3, 1947 

